Electric measuring instrument.



PATENTBD OUT. 10, 1905,

E. TEGMSON BLEUTRIG MEASURING INSTRUMENT.

APPLICATION YILED F3115. 1905.

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PATENT orrron. v

nLmejrHoi/rsoii, or sWAMPsoo'rr, MASSACHUSETTS; ASSIVGNOR' To GEN AL ELECTRIC COMPANY, aconr onArron-or NEW YORK.

arse-talc mssscame merepmsur.

five seine. I

Te all whom, it may concern;

Bea known that LELIHU Tnigigzon, we

1 to ing; instruments, such'as-volt'meters and wattmeters'; and its object'is to effect certam imentsiofithis type whereby an inexpensive d reliable instrument, is- .obtained, which 'jveaccui'ate readings with reference to. A e extending over a large angle and havathe scaleemarkings thereon evenlydis- .trihuted... i-

1' I y j,

.-'=-.i'-.'Qn'e of the features of novelty of my inven- I so. ti'on lies intthe arra gement of the coilof the moving1element, .ET coil is wound within indicator, The wi th, of thecoil is the same J -as that .of the'plate, andtherefore the length :of 'the air-gap' of the magnets can be reduced 1 iTh'e ma netic field is therefore a strong one e is.small,so that the torque of 'j the moving e ement is high. Also if perma- 'wnent: magnets are used they will remain of more nearly con'stant stren 'th than, if a largerJaiEgap "were employed. 1 The 'coil' is 1 preferably circular, and the pole ends of the j" magnets are rounded off in such a way that the'movement of the movingelement fora ogivenvariation of the currentor voltage will the same atallpoints in the range of -movement of the indicator. This ives f evenly distributed scale-markings; but if hesird,; tliev shape of the coil and the pole ends of the magnets may be varied to make the scale-markings more open at one point than another-as, for instance, more open about the nornial running-point of a generator.

Another'feature of my invention is the arso rangement of the spring which furnishes the;

f'zero-seeking force. For this (purpose I em- ,ploy along helicalsprinv-an secure both its ends to the shaft of the moving element Specification 6f Letters .Patnh 1 v Application filed February 15 -1905- Sorial No. 5,751. I

.,Tliis*' vention relates to electric measurprovements in the eonstructionoi metro-- meter, as the. novel-form of coil is best .ada t' upon which are mountedatwo permanent magnets 2and 3.

is a-standard 4 in the end of which is"a'-bear -ailaii'geopening in the .thin metallic plate} whichoooperates with the permanent .or .elec' troma gnets to dam en the movements of the tea The len th of the gap need.

Iatmited Oct. 10, 1905.

and its middle portion to a stationary part of the instrument. By thisflarrangement both halves of the spi ting act together to restore the moving element" to-the zero position. e The novel features of my invention will be better understood by reference-to the following description, taken inconnection with the Figure 1 is a plan view of the instrument,

broken awa in part. 2 is a section of 6s a portion 0 the instrument, and Fig.3 is a perspective view of the moving element. In the drawings l-have shown my improve ments embodied in a direct-current 'volted for this use; but I wishit understood t at my improvements are -ap 'licable generally to measuringinstruinentso all'classesm j r Iteferriiig to the'drawin' s', 1 .indicatesa.

Secured to the base 1 ing 5 for one end of the shaft 6 of the movin element, the other end of which is supportedin a bearing 7, mounted on the baseLL-Se- 8ocured on shaft 6 is a plate 8, with curved ends as shown'in Figs. 1 and 3, in which isalarge round opening on one side of the shaft. This plate, besides carrying the coil of the moving element, cooperates with the magnets 2 and 3 to dampen the movements of the indicating system and is preferably inade'of aluminium, so that the ratio of the weight of the moving element to the torque of the instrument'will be as large'as possible. The-coil 9 of the moving element is mounted within the opening in plate 8. It is of rectangular section, as shown in Fig. 2, and its width-is preferably the same as the width, of the plate. The coil is held in position and the vseveral turns of the coil are held together by a thin filmof varnish, witlrwhich it'is coated. The-ends of the coil are secured to a supporti "-disk 10, of insulating material, mounted ons aft 6, from which oneofthe wires extends up along an insulating-sleeve oil the shaft to the inner e'nd'of a flexible spiral 11, the outer end of which is" secured to a pin 12, fextending through the standard i but insulated there- 'from by a suitable'bushing. The other end 1e5- I of the coil 9 is connected to the end ofa see .65 accompanying drawings,which show thegrew I 'feirl'ed embodlment of my invention, an in '.'ch

' insulated therefrom cud flexible spiral 13, secure v on shattlj, an from the other end ofcoil S) bya sleeve 1,4, of insulating material.

The other end of-this spiral' is secured to a second pin 15, extending through but insulated from standard 4.

' and 3 have the poles drawn together closely to form small air-gaps..

- mounted in an opening in e add to the width of theportion of the niovlong. period of. use of The coil 9 being plate 8 does not ing'element, which moves in the fields of :the magnets, and therefore the ups of the mag- I nets can be made verysmal 'witlrthe resultant advantages of a strong field and a small amount of leakage. Also on account of the small gap the strength of the magnets will re- 'main more nearly constant throughout a the instrument. The pole'endsof the magnets are so shaped that the-coil moves out of the fieldas' the moving 3 element turns on its pivot atf'just the'rate necessary to give the desired {spacing o gscale;

distribution of the scale-markii'igs. pill) the drawings 1 have shown the pole ends rounded .oll'onthe corners aWav-J ilroin th'e shaft ;to ve an even i l' the 'ni'nrking s throughout. the

Tlieiero-seekin'g force is"suimlied bvf a long ,helici tlspring 18, which surrounds shaft middle portion of "6 and .hits-both'endls attachedthereto. The this springis seeurml to the end off a hr'acketlfi, inount'ed on the base 1 the: moving elewoiind'gn'p V and-Ythe other half I unwound, so

that both of ftlie sections tend, to bring the moving:element; back to thezero )(JSltiOll. ObviouslPthis a'rrangement could be reversed,'-"i desii'ed,'-+-that is, the middle portion of the spring could be s cure d-, to' the sh aft'nml -the ends to stationary, portions of the. 1nstrument.-

- In thesides of theinstruiiient are tivo bindlated pin 15,

' cured on the base of. the instrument.

other sidcof the spools ls connected,through a switch 2(i,operatedfrom outside the casing,

ing-posts21and 22, by which the instrument is connected in circuit. .p-Bmdmg-post 21 1s connectcdby a lead 23 vvith the insulated pin '12, supported on standard 4, from which con-' nection is made by the. flexible spiral 11 to the moving coil 9. The other end of the coil is connected, through the which isr-onnectedby a lead 24 25 of resistance-wire se- The to a series of spools of the instrument, to the binding post 22. Mounted above the spools is ascale-plate 27 over which an indicatingneedle 28, secure( to the shaft 6, moves;

What 1 claim as new, and desire to secure- 'by Letters Patent of the United States, is5

1. An electric measuring instrument com:

prising a magnet having a small air-gap, a metal damping-plate movable in the mag: net c held with small clearance, and a current- The permanent magnets 2 ing a pivoted shaft, 'openingtherethrou h opening, .means for conthellielil of. which the coil is of the springing, means l' or .(mnnecting spiral-1.3 to the 'insumeasuring coil carried by the plate through theffield and bounded by planes coincident with those which bound-the plate.

2. An electric measuring instrument havin means for establishing a magnetic field, a thin metallic platehaving an openin there through movable in the magnetic fiel a coil mounted in said opening, and means for connecting the coil in circuit.

means for connecting the coil in circuit, and

'a magnet mounted in (position with its oles closely embracing sai plate in the fie d of \vhichthecoil is adaptedtoinov'e.

5'. Anielectric measuring instrument'hava thin late having an carried by the shaft, a

coil mounted -in sai net-tin the coil n circuit, and a magnet in 6. An electric measuring instrument hav-' ing means for establishing a magnetic field, a pivoted shaft, a thin metallic plate carried thereby movable in the magnetic field, said )latehaving an opening therethrough on one side of the shaft, a-eoil-mounted in said open--.

ing, and means for connecting curt.

the coil in eir- 7. An electric measurmminstrument having a pivoted shaft, a thin metallic plate carried t lereby having anopening therethrough on one side of the shaft, aeoil in said open.-'

and two permanent magnets mounted in position with-the poles embracing the plate on opposite sides of the shaft.- I i 8. An elect 'c measuring ihstrumenthaving a )ivoted shaft, a thin metallic plate carried t ierehy'havin r an opening therethrough of 'a thicknessnot greater than thsjt'nf the plate, means for connecting the. 1n .eir-- euit, and. two permanent magnets mounted in position wit 1 the poles closely embfiaeing .the plate on opposite sides of the. shaft) the coil and poles being so shaped'rlatively that a d elinite increase of current in the coil causes substantially the same movement of the moving element of the instrument in all positions of said element.

9. An electric measuring instrument having a pivoted shaft, a thin metallic plate carried t iereby havim an opening therethrough on one side of the shaft, a coil in said opening thickness not greater mounted in said opening,

adapted to move.

the coilin circuit,

'on one side of the s mi t, a coil insaid opening ssmm of a thickfi ess not; greater than phat of the piste, means for connecting the-boil in circult, and two ei-manent magnets mount-ed in pssiizimi wit l the poles ciaseiy embracing the plate on opposite sides of the shaft, andiisving .he corners of the psis ends away from the shaft rounded mi,

50. In an siecmqmeasm'mg instrument, &

- pivbtsci shsf an indicstsr carried thereby,

and a spr ng ts retract the indicator baths a port-ion intsrmedists the ends sec-u: 3d ens zero position, said spring having its (m ls and 11. In a, measuring instrument, a pivot-ed shaft, an indicator carried thereby, and a helical spring to retract the indicator to the zero position, having its ends secured to the shaft and a portion intermediate the ends secured to a stationary portioii' of the instrumens.

In Witness whereof I have hereunta set my hand this 13th day of February, 1905.

Y ELIHU THOMSUN.

Witnesses JOHN A. IViUBIAiTUS, J12, DUGALD M0151. IVIGKiLLQP. 

